The title points us toward the theme and the puzzle answer. All the answers that end in 8 have something in common:

8d [“Darn!”] = NUTS.

FB contest, “Numbers Game”, solution grid

18a [Away from one’s desk, perhaps] = OUT TO LUNCH.

28d [Super Bowl 50 national anthem singer, familiarly] = GAGA.

38a [Split parts] = BANANAS.

48d [Like velcro] = LOOPY.

58a [1987 Best Picture nominee] = MOONSTRUCK.

They’re all synonyms for “crazy.” They are the CRAZY EIGHTS, which in turn is an anagram of two other answers, ITCHY and GRAZES. I recognized the thread connecting the longer across themers and completely missed the rest. Bow of admiration to Don and Zhouqin, and to the 76 people who submitted the correct answer.

A few other things:

5d [Dive smoke] took me a while to figure out. One might smoke a STOGIE in a dive bar.

Updated Chicago politics reference: RAHM instead of Daley.

The last square I filled in was the crossing of 51a [Hand punch?] and 51d [FBI guys.] I always figure government agents can be either T-MEN or G-MEN (although I suppose T-men work for Treasury, not the FBI) and I couldn’t figure out [Hand punch?] at all. I had a typo in 51a as well, which didn’t help. Turns out it’s GMEN and GROG, which is the punch drunk by deck hands. Ah-hah.

What I didn’t know before I did this puzzle: that Patsy CLINE was the first female solo performed inducted into the Country Music Hall of Fame. I wonder if they tucked her in there because she will forever be associated with this standard.